Process of producing phosphate fertilizer



. Patented Apr. 7, 1936 2 03 494 UNITED. STATES PATENT OFFICE PROCESS OF PRODUCING PHOSPHATE FERTILIZER James K. PIummer AtIanta, 6a., assignor, by mesne assignments, to Tennessee Corporation, New York, N. Y., a corporation of New York No Drawing. Application March 26, 1930, Serial No. 439,223

Claims. (Cl.'71---'I) The present; invention relates to the producof water and ammonia usually in the form of aqua tion of phosphate material containing ammonia ammonia. ,The strength of the aqua ammonia is and more particularly to a phosphate fertilizer such that the resultant mixture will have an having ammonia incorporated therein and toacidity corresponding to the desired acidity re- 5 a process of producing the same. I quired for the acidulationof the phosphate rock Heretofore attempts have been made to provide or other phosphate-bearing material. The aqua a phosphate fertilizer which contained ammonia. ammonia is preferably of such strength that it One of the proposals which was suggested was will dilute the sulphuric acid of about 60 to 66 the addition of ammonia usually as a pure or di- Baum to an acid equivalent of about 50 to about in luted gas or as liquid anhydrous ammonia, to a 55 Baum. When the aforesaid resultant mixll) soluble phosphate-bearing material and a sulture is tested with a hydrometer due consideraphate-bearing material under such conditions tion must be given to the fact that ammonium sulthat a mixed fertilizer would be produced conphate is present. This means that the resultant taining a soluble phosphate and ammonium salt. mixture having the proper acidityspecified here- Experience has shown that the maximum amount inabove will show a density depending on the 15 of ammonia capable of being incorporated by the amount of ammonia used and its acidity can aforesaid proposal in a ton of fertilizercar'rybest be measured by titration. It will run 60 ing 12% P205 was 34 pounds of ammonia. At to 70% H2804. The temperature of the mixture tempts to produce fertilizers with a higher amwill be somewhere in the region of that "oil boilmonia content showed that there was a reversion ing water. 20

of a portion of the phosphate to insoluble forms. Before the mixture is used, I have found that Another attempt to provide a phosphate fertiit is highly advantageous and essential to cool lizer containing ammonia was a proposal to mix the same to a substantial extent. In practice aqua ammonia in a desired ratio with about 60 I have found that satisfactory results canbe ob u p i c d j at r prior to the time tained by cooling the mixture to approximately 25 when the acid reached the mixing pan where it 100 to 115 Fahrenheit. At this temperature was mixed with ground phosphate rock. When I use the mixture containing diluted sulphuric this process was attempted to be carried into acid and ammonium sulphate for reaction with practice it was found to develop troubles, such as phosphate rock ground so that 90% pa an spattering and sputtering which caused loss of 80 mesh screen. The reaction between the afore- 30 material, inconvenience of handling and annoysaid mixture and the ground phosphate rock can ance to the operator. be carried out in any suitable apparatus but I It is an object of the present inv ntion to overprefer to conduct the reaction in the mixing pan come the disadvantages of prior processes noted commonly used for making phosphate fertilizer.

hereinabove and to provide a satisfactory am- In cooling the mixture containing sulphuric 35 moniated phosphate fertilizer and a practical acid, ammonia sulphate or water,anyappropriate process of producing it. apparatus can be used. For instance, the hot ot Obje t 15 to co r l the temperature mixture can be held in a tank which can be cooled of the reacting materials so that they will be by cooling coils mounted therein. By permitting 40 contacted with each Other under optimum condicool water to flow through the cooling coils the 40 tions of heat. temperature of the mixture can be reduced to any A further abject is to provide an ammoniated desired degree. phosphate fertilizer which can be produced in a In the event that the tank method of coolin good mechanical condition and which will be free is not appropriate or available then the mixture from stickiness due to free phosphoric acid. can be cooled by passing the heated mixture down 45 A still further object of the invention is to through a cooling tower while a stream of air is provide a, process of producing an ammoniated being passed upwardly to cool the mixture. Simphosphate fertilizer. in. .which any desirable ilarly, the hot mixture can be cooled by placing amount of ammonia can be incorporated in the it in a vessel under vacuum and removing some fertilizer. of the water by evaporation. The evaporation of 50 Other objects and advantages of the invention the water, as it is well known, will cause cooling of will become clear from the followingillustrative the body of liquid contained in the vessel. example. 7 When the cooled mixture containing diluted In carrying my invention into practice, I take sulphuric acid and ammonium sulphate is used sulphuric acid and mix th: same with a mixture as set forth hereinabove no spattering or sputter- 55 ing occurs and a phosphate fertilizer containing ammonium is produced.

- The ammoniated phosphate fertilizer produced as described hereinabove is preferably treated with further amounts of ammonia in the form of aqua orgaseous ammonia. The amount of ammonia added can be varied depending upon the percentage desired in the final phosphate fertilizer. In practice, I prefer to add 120 lbs. of

aqua ammonia having a strength of about 30% to every ton of ammoniated phosphate fertilizer. The ammonia thus added can .vary in amount from say, 5 lbs. to about 35 lbs. per ton of fertiliz er.- By the use of this treatment I am enabled to increase the amount of ammonia in the fertiiizer and, at the same time, free the fertilizer from stickiness and to improve its mechanical condition. If this treatment is omitted the am-.- moniated fertilizer has a tendency to be sticky and not to be in good mechanical condition. In

cases'where mechanical condition and stickiness are not controlling factors this last treatment can be omitted, but in commercial practice, however, it is desirable and in some cases essential to have the fertilizer free from'stickiness and in good mechanicalcondition and consequently I prefer to utilize the second treatment. Furthermore, theamount of ammoniaor the nitrogen content contained in the fertilizer can be varied as desired by proper selection of strength of aqua ammonia and the selection of the proper concentration of sulphuric acid.

Although I have described one specific method ofcarrying my invention intopractice it will be observed that any modified method. or appropriate method can be used to carry out my method and that the description of a particular way of ca ying my method into practice is not to be taken as a limitation of the invention.

My improved phosphate fertilizer produced in accordance with my method outlined hereinbefore may contain 12% of soluble P305 and more than 40 lbs. of ammonia per ton of fertilizer. The percentage of P200 may vary from 2% to 16% andthe ammonia can vary from 2% to 8% in my finished fertilizer. The percentage em- 7 ployed in any given case will depend upon the requirements of the market. v

While I have described a specific example of my improved fertilizer and process merely by way of illustration, it is to be understood that I am not to be confined to the exact steps nor the specific materials given as they are to be regarded only as illustrative and typical. Various modiflcations may be made without departing from the spirit of my invention as defined in the appended claims.

I claim: 1. 'A process for the production of a phosphate fertilizer containing" nitrogen which comprises treating phosphate rock with sulfuric acid of over 54 B.racid strength containing ammonium sulfate in solution.

2. A process for the production of a phosphate fertilizer containing nitrogen which comprises treating phosphate rock with sulfuric acid of over 54 B. acid strength containing ammonium sulfate in solution and treating the resulting productwith ammonia.

3. A process for the production of a phosphate fertilizer containing nitrogen which comprises treating phosphate rock with sulfuric acid of about 55 B. strength containing ammonium sulfate in solution.

4. A process for the production of a phosphate 1 fertilizer containing nitrogen which comprises treating phosphate rock with sulfuric acid of about 55 B. strength containing ammonium sulfate in solution and treating the resulting v product with ammonia.

5. The process of producing a phosphate fertilizer containing nitrogen which comprisesw-p'artially neutralizing sulfuric acid with ammonia to produce an ammonium sulfate-sulfuric acid solution in which-the ratio of free acid to water corresponds to an acidconcentration of about at least 54 B., reacting said solution with phosphate rock, and treating the resultant product with ammonia-r JAMES K. PLUMMER. 

